|Publication number||US8051869 B2|
|Application number||US 12/470,903|
|Publication date||Nov 8, 2011|
|Filing date||May 22, 2009|
|Priority date||May 22, 2009|
|Also published as||EP2261539A2, EP2261539A3, US20100294371|
|Publication number||12470903, 470903, US 8051869 B2, US 8051869B2, US-B2-8051869, US8051869 B2, US8051869B2|
|Inventors||Francis Parnin, Enzo Dibenedetto|
|Original Assignee||United Technologies Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (34), Non-Patent Citations (1), Referenced by (4), Classifications (11), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Reference is made to application Ser. No. 12/470,823 entitled “WINDMILL AND ZERO GRAVITY LUBRICATION SYSTEM” and application Ser. No. 12/470,875 entitled “APPARATUS AND METHOD FOR PROVIDING DAMPER LIQUID IN A GAS TURBINE ENGINE” which are filed on even date and are assigned to the same assignee as this application, the disclosures of which are incorporated by reference in their entirety.
Reference is also made to application Ser. No. 12/393,743 entitled “AUXILIARY PUMP SYSTEM FOR FAN DRIVE GEAR SYSTEM”,filed on Feb. 26, 2009 by William G. Sheridan and is assigned to the same assignee as this application, the disclosures of which are incorporated by reference in their entirety.
The present invention relates to valves, and more particularly, to valves actuated by gravity for use in gas turbine engine lubrication systems.
In many gas turbine engines, a low pressure spool includes a low pressure turbine connected to and driving a low pressure compressor, and a high pressure spool includes a high pressure turbine connected to and driving a high pressure compressor. A main pump is typically driven by the high pressure spool, connected through gearing, and is used to pump lubricating and cooling liquid to all engine components that require lubrication and cooling.
The main pump typically pumps liquid from a passage connected to a main reservoir that holds both liquid and air. During normal operating conditions, the liquid settles at the bottom of the main reservoir and displaces air to the top. However, in a gas turbine engine mounted on an aircraft, the main reservoir may experience reduced gravitational forces or “negative gravity” conditions such as the aircraft turning upside down, the aircraft accelerating toward the Earth at a rate equal to or greater than the rate of gravity, or the aircraft decelerating at the end of a vertical ascent. Under negative gravity conditions, the liquid in the main reservoir can rise to the top, which can expose an opening of the passage to air and interrupt the supply of liquid to the main pump and, consequently, interrupt supply to the engine components. Certain engine components, such as gears and bearings, can be damaged by a relatively short period of non-lubricated operation during negative gravity conditions.
In some gas turbine engines, a fan at the front of the engine is connected to the low pressure spool through a fan drive gear system. When the high pressure spool stops rotating or rotates at a reduced rpm (revolutions per minute), the fan drive gear system can continue rotating even though the main pump will ordinarily provide little or no liquid during this time. For example, wind may rotate the fan and corresponding gears and bearings while the aircraft is parked on the ground or during an in-flight engine shutdown. Certain gears and bearings can also be damaged by a relatively short period of non-lubricated operation during windmilling as well.
According to the present invention, a valve includes a valve body defining a valve cavity. The valve body has first and second inlet ports, an outlet port, and a dump port. A weighted member is positioned in the valve cavity and is movable between first and second positions. In the first position, the first inlet port is fluidically connected to the outlet port and the second inlet port is fluidically connected to the dump port. In the second position, the second inlet port and the dump port are fluidically connected to the outlet port.
Another embodiment includes a method of operating a valve. The method includes flowing fluid from a first inlet port to an outlet port and from a second inlet port to a dump port when the valve experiences gravitational forces exceeding a threshold, and flowing fluid from the second inlet port and from the dump port to the outlet port when the valve experiences gravitational forces less than the threshold.
Yet another embodiment includes a method of operating a valve having a valve body and a weighted member. The method includes flowing fluid from a first inlet port to an outlet port and from a second inlet port to a dump port when the weighted member is in a first position with respect to the valve body, applying a pressure from the second inlet port tending to bias the weighted member toward a second position with respect to the valve body, and flowing fluid from the second inlet port to the outlet port when the weighted member is in the second position.
Pump 44 is coupled to and is driven by fan shaft 34 via pump gear 46 such that pump 44 can operate whenever fan shaft 34 is rotating. Pump 44 supplies liquid, such as oil, to lubricate components such as gears and bearings of fan drive gear system 36. Fan drive gear system 36 benefits from a relatively continuous supply of lubricating liquid whenever fan shaft 34 is rotating. At least some of the liquid supplied to fan drive gear system 36 drains to sump 48 and is eventually pumped back through pump 44. In an alternative embodiment, pump 44 can be an electrically driven oil pump.
As fan drive gear system 36 spins, lubricating liquid drips or flies off fan drive gear system 36 into bearing compartment 52 in different directions. A portion of that liquid is caught and collected by gutter 56 and funneled to auxiliary reservoir 58. During normal operating conditions, auxiliary reservoir 58 is kept substantially full of liquid for later use. In one embodiment, auxiliary reservoir 58 contains enough liquid to provide adequate lubrication for fan drive gear system 36 for a specified amount of time. Gutter 56 does not collect all liquid leaving fan drive gear system 36. The remaining liquid that is not collected by gutter 56 falls to sump 48, which is an open-top reservoir at a bottom of bearing compartment 52. Bearing compartment 52 can be sealed to reduce liquid flow out of bearing compartment 52, except through designated passages as herein described.
Second shuttle valve 62 is fluidically connected to auxiliary pump 44 via passage 76, to main pump 66 via passage 78, to bearings 54 via passage 80, and to main reservoir 64 via passages 82 and 88. In the illustrated embodiment, passage 76 is an auxiliary supply passage and passage 78 is a main supply passage. Second shuttle valve 62 selectively directs fluid flow from auxiliary pump 44 or main pump 66 to bearings 54. Main reservoir 64 is further connected to main pump 66 through passage 84. Scavenge pump 67 is connected to sump 48 via passage 86 and to main reservoir 64 via passage 88. Scavenge pump 67 pumps a portion of the liquid in sump 48 to main reservoir 64 for use by main pump 66. (See application Ser. No. 12/470,823 entitled “WINDMILL AND ZERO GRAVITY LUBRICATION SYSTEM” filed on even date and assigned to the same assignee as this application for a more detailed description of the function of second shuttle valve 62).
First shuttle valve 60 is fluidically connected to auxiliary reservoir 58 via passage 68, to sump 48 via passage 70, to auxiliary pump 44 via passage 72, and again to sump 48 via passage 74. As part of pump system 50, first shuttle valve 60 and second shuttle valve 62 work together as a valve system. This valve system directs lubricating liquid to bearings 54 from one of sump 48, auxiliary reservoir 58, or main reservoir 64. When engine operating conditions prevent main pump 66 from supplying adequate liquid, second shuttle valve 62 switches from main pump 66 to auxiliary pump 44. Switching to auxiliary pump 44 can be beneficial if it has an adequate supply of liquid from first shuttle valve 60 during all gravity conditions.
First shuttle valve 60 is actuated by gravity to selectively direct fluid flow from auxiliary reservoir 58 or sump 48 to auxiliary pump 44. Actuation depends on whether gravitational forces are sensed to be above or below a threshold. Forces from the Earth's gravitational field do not, of course, actually change at a given location. Instead, the term “gravitational forces” as used herein refers to forces from the Earth's gravitational field combined with inertia to create what is sensed to be gravity conditions at a particular point in time by a particular object, such as first shuttle valve 60. For example, gravity conditions can be sensed to be ordinary, zero, or negative. Ordinary gravity conditions can occur when gravity is sensed to be positive, such as when gas turbine engine 10 is vertically upright and parked on the ground, flying level, ascending, or gradually descending. Negative and zero gravity conditions can occur when gravity is sensed to be approximately zero or negative, such as when gas turbine engine 10 is upside down, accelerating toward the Earth at a rate equal to or greater than the rate of gravity, or decelerating at the end of a vertical ascent. Ordinary gravity conditions include weighted member 92 experiencing gravitational forces greater a threshold that is equal to a value between about 0 and 1 times the force of standard gravity at sea level (also called “g-force”, “g0”, or “gees”). In one embodiment, the threshold can be about 0 g. In another embodiment, the threshold can be a value greater than about 0 g but still less than 1 g.
Under zero and negative gravity conditions, liquid in sump 48 and main reservoir 64 can rise to their respective tops, interrupting supply to passages 70 and 84, respectively. On the other hand, auxiliary reservoir 58 is kept substantially full of lubricating liquid and is adapted to supply that liquid during negative gravity conditions. In one embodiment, however, auxiliary reservoir 58 only holds enough liquid to supply for a limited amount of time, as dictated by aircraft mission requirements. Auxiliary reservoir 58 does not capture liquid efficiently enough to supply the liquid for long durations. Thus, first shuttle valve 60 supplies liquid from sump 48 to auxiliary pump 44, under ordinary gravity conditions, which is most of the time. First shuttle valve 60 then switches and supplies from auxiliary reservoir 58 only for brief periods of zero or negative gravity.
Rotational speed of high pressure spool 20 is important because main pump 66 is driven by high pressure spool 20. If high pressure spool 20 rotates slower than operating speed or even stops, then main pump 66 will pump a reduced amount of liquid. In some situations, fan 32 can continue rotating at relatively high speeds when high pressure spool 20 rotates slowly or even stops. This can occur when gas turbine engine 10 is shut down but air still flows across fan 32, such as during an in-flight engine shut-down or when gas turbine engine 10 is on the ground and fan 32 is “windmilling”. For these reasons, it can be important that first shuttle valve 60 supply fluid from sump 48 when gravitational forces are above a threshold and supply fluid from auxiliary reservoir 58 when gravitational forces are below a threshold.
When first shuttle valve 60 is used in pump system 50, it can be connected to the various passages as illustrated in
Under ordinary gravity conditions, gravity acts on weighted member 92, pulling weighted member 92 down and holding it in the first position. Fluid flowing in second inlet port 98 creates a pressure in bottom sub-cavity 106, tending to bias weighted member 92 up. Despite this fluid pressure, weighted member 92 will be held in the first position so long as gravitational forces are greater than a threshold.
When transitioning between the first position and the second position, fluid from first inlet port 96 still flows to outlet port 100. However, now fluid from second inlet port 98 flows in bottom sub-cavity 106, through sleeve sub-cavity port 114, through main sub-cavity 104, through bottom sleeve side port 112, through side sub-cavity 108, and out outlet port 100. If a pump such as auxiliary pump 44 creates a sufficiently low pressure area at outlet port 100, fluid from second inlet port 98 will no longer flow out dump port 102. Instead, fluid will enter dump port 102, mix with the fluid entering second inlet port 98, and flow out outlet port 100.
When gravitational forces acting on weighted member 92 are below the threshold, valve 60 supplies lubricating liquid from auxiliary reservoir 58 to auxiliary pump 44. Also in the second position, valve 60 can supply air from bearing compartment 52 through valve port 102 to auxiliary pump 44. Air bleeding in through valve port 102 can mix with and dilute lubricating liquid entering through second inlet port 98 to extend the length of time it takes auxiliary pump 44 to empty auxiliary reservoir 58. This extends the amount of time auxiliary reservoir 58 is able to supply lubricating liquid during zero and negative gravity conditions. Depending on the exact configuration of pump system 50, some lubricating liquid may enter valve port 102, in addition to air, to mix with the lubricating liquid entering from second inlet port 98.
It will be recognized that the present invention provides numerous benefits and advantages. First shuttle valve 60 can effectively switch between multiple inlet sources, actuated by gravity. This allows for pump system 50 to supply lubricating liquid to certain components during windmilling and during negative gravity conditions. Because of the size, weight, and configuration of first shuttle valve 60, it can be positioned conveniently in bearing compartment 52, reducing the need for additional valves and additional piping. This can reduce the overall weight of pump system 50, and consequently, gas turbine engine 10. First shuttle valve 60 can also be relatively reliable and low maintenance by virtue of having only a single moving piece.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. For example, first shuttle valve 60 is not limited for use in pump system 50. Instead, first shuttle valve 60 can be used in virtually any system that benefits from a gravity actuated shuttle valve as configured in the present invention.
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|U.S. Classification||137/1, 137/597, 137/533, 137/38|
|Cooperative Classification||Y10T137/0318, Y10T137/7909, Y10T137/0753, Y10T137/87249, F16K17/36|
|May 22, 2009||AS||Assignment|
Owner name: UNITED TECHNOLOGIES CORPORATION, CONNECTICUT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PARNIN, FRANCIS;DIBENEDETTO, ENZO;REEL/FRAME:022726/0250
Effective date: 20090520
|Apr 28, 2015||FPAY||Fee payment|
Year of fee payment: 4